Some of this country's most common professions, from trucking to nursing, can also be its most dangerous because they can make you the fattest. They involve little exercise, lots of stress, and long hours of sitting. And for the people you're about to meet it meant major weight gain. Until their bosses stepped in with an unusual offer. Cash to slim down. Here's abc's ryan owens. Reporter: Truckers haul millions of tons across this country every day. Maybe it's no surprise they put on a few along the way. Well, lots of times I do up to 60, 70 hours in a week. Reporter: Troy robbins is typical. He drives up to 700 miles a day, spends up to 14 hours every day sitting right here. And when he stops at a truck stop, his dining choices range from grease to greasier with a side of sugar. Before long the 47-year-old weighed nearly 500 pounds. And the prospect of losing it seemed as grim as the selection back at the truck stop. He has plenty of company. One study found a whopping 86% of this nation's 3.2 million truck drivers are overweight or obese. Trucking is always near the top of the list of jobs that make people fat. So is manufacturing and clerical. All of that time sitting. But here's one that might surprise you. Health care workers. But in of all places milwaukee, wisconsin, home of brauts and beer, where trans fats are nothing short of an essential food group, they're trying to do something about it. Milwaukee is also home to aurora health care, wisconsin's largest private employer. Oh, my goodness. Reporter: Marianne scherer works as a mid-wife at aurora's downtown hospital. We have a lot of long hour shifts, a lot of erratic shifts, and I think it's a high stress job. Reporter: The one-time fitness zrushlth says the stress of teaching nurses all day -- CONTROLLED SUBSTANCE. Reporter: -- and delivering babies all night -- all right. I'm going to give you a hand. Reporter: -- Has taken a toll on her waistline. P not a lot of salads at 3:00 a.M.? No. Salads aren't delicious at 3 in the morning. Pasta, donuts, candy incredibly delicious at 3:00 in the morning. Reporter: But marianne came one a competition. Marianne and four other delivery nurses and mid-wives formed the team, the birthing babes. They competed with 200 other teams from aurora to see who could lose the most weight. The winning team could get $10,000. Which provided enough motivation to get the birthing babes to power-walk along milwaukee's frigid lakefront. Before it was hey, let's go out for lunch, let's go, you know, out for dinner. And now it's hey, you want to get together and go for a walk? Let's go to zumba. Reporter: Which would have sounded crazy a year ago. Oh, absolutely. I'd be like zumba, are you out of your mind? You don't have to go to the jm. You go to the park. You walk the hills. You take a bike ride. You can do it if you watch what you put in your mouth. Reporter: Their employer helped with that too. Aurora opened dining options that look more like a health food store than a hospital cafeteria. A tuscan kale salad in wisconsin? Yes. And it's been a big hit. The birthing babes' motivation to keep moving? They want the 10 grand for a trip to hawaii. I've been on about, I don't know, 15 diets in the last nine years since I had my kids. And it was all about my diet. Well, now it's about my family, my diet buddy's diet. And it's not only about me. It's about them. If I don't meet my goal, I'm disappointing everybody else in our group. And it's great to be able to text somebody and say oh, god, i really want a donut right now and for them to say go work out or drink some water or eat some carrot sticks, or you can do this, until that craving passes. Reporter: I mean, it sounds cheesy, but it works, right? It does. That's old school. Jordan. Reporter: Marianne says as health care workers they have an additional motivation. Our image to our patients. Look what we've fallen down to. We're not perfect. We don't eat great. But there's a way you can do it. Even if you're as busy as we are. Reporter: Remember troy? He had a unique incentive to hit the gym. Something more valuable than money. After his wife died of cancer, his sons confronted him. Especially my 13-year-old. He's the one that said "dad, do it." You've got to get healthy. To hear it come from him I guess is what motivated him to get it done. Reporter: Troy promised he would, even though as a single dad he needed his sedentary job more than ever. Your job is to sit on your butt for 11 to 14 hours every single day. Yes. Every day. Reporter: Enter bob perry. Also working your back. Reporter: A sort of fitness guru for the long haul trucker. He taught troy to use his big rig as a gym. From walking laps around it to stair steps on the step rail. Use your legs to push out. Reporter: To push-ups on the side. Inhale at the easiest point and exhale at the point of -- Reporter: To squats off the grill. This is a tough gig. This is not easy pop so they're not lazy. It's just they've never paid attention to bringing a solution. That's what this is all about. Reporter: Bob's initiative is called rolling strong. Along with the big rig gym he's designed a workout system for inside the truck. He sold more than 2,000 of these band systems for $70 a pop. They allow truckers to work out in the comfort of the cab, even in nasty weather. Good job. Reporter: How much of this is about making it convenient for them? It's all about it. It's all about it. Reporter: Bob's company has also opened fitness centers at four truck stops and is working with them to offer healthier options. Fewer corn dogs and donuts. Is there a culture out there that says wait a minute, this doesn't look right to have a guy working out around his truck or this doesn't feel right to have healthy things at the truck stop? Is there a culture? Absolutely. And this is what this is about. It's a shift in the culture. And it's not easy. They realize they have to make a change and they want to make a make it more accessible. Reporter: It's working. Using his truck as a gym and eating better have helped him lose 85 pounds for his teenage son. And he's not done yet. His message to those struggling with weight? Take 30 minutes. It's not that hard to take 30 minutes out of your schedule. I know if I can do it anybody can do that. Reporter: Back in milwaukee the birthing babes did it. They lost 88 pounds. They didn't win the 10 grand because so many of their co-workers lost even more weight. During the eight months of the competition aurora's 30,000 employees lost a total of 20 tons. The nurses say anyone can do it. Just get moving. Get off your butt and get moving. Reporter: I'm ryan owens for "nightline" in milwaukee.

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